There are a number of switch devices in the prior art adapted to be interposed between the storage battery and the electrical system of an automobile. The purpose of these devices is to provide a means for interrupting or breaking the electrical circuit so as to isolate the battery. This promotes safety and helps avoid fires by preventing accidental starting and eliminating short circuits. Also, the components of the electrical system can be worked on without fear of causing a short circuit that could damage component parts due to the high current loads available from the battery. Such switch devices also find utility in preventing depletion of the battery from small leaks to ground in the electrical system, as are often present in older vehicles of the classic or antique type, and as theft prevention devices.
The prior art includes breaker type switches wherein a removable breaker element is manually inserted and removed from between two contact members to make and break the electrical circuit, respectively. Two such devices are shown in the patents to Dunn et al, U.S. Pat. No. 2,801,399, and to Salters, No. 4,092,506. These breaker type switches are operable only at the switch juncture.
Remotely operated battery switches are shown in the U.S. Pat. Nos. to Minch et al, No. 2,538,581 and Karl, No. 2,853,627, as well as the French patent to Palau, No. 814,033. A chief drawback of each of these switch assemblies is a tendency for electrical current to arc between a movable contact and at least one stationary contact during switch disengagement. Such a problem is effectively eliminated by the snap action disengagement in the present invention. The safety switch in Karl also suggests a push-pull contact assembly having no mechanical advantage to reduce the contact engagement pressure of the biasing spring member. Regarding Palau, only one electrical contact is employed, whereas double contacts are preferred in order to insure positive interruption of the electrical circuit when the switch is open, especially since foreign materials can build up between contact surfaces. The contact element of Palau is also subject to frequent flexure which causes stress fatigue and can result in rapid failure.
Such prior art devices have a number of other significant disadvantages. Contact surfaces and other internal parts are exposed to moisture and other corrosive materials. Because many known switches are often mounted directly upon the battery terminal, they are subject to the corrosive action of battery fluids and terminal deposits.